Field of the Invention
The embodiments of the invention relate to a guardrail extruder head, and more particularly, to reinforced guardrail extruder head.
Discussion of the Related Art
In general, a guardrail extruder head is located at the oncoming traffic ends of guardrail runs. The guardrail extruder head is designed to deflect a side impact by a vehicle and, in the alternative, absorb a head-on or shallow angle impact by a vehicle. A guardrail extruder head absorbs energy from a head-on impact to its impacting head by receiving a W-beam guardrail though a feeder chute, flattening the guardrail beam in an extruder throat by squeezing the W-shape out of the guardrail beam, and then deflecting the flattened guardrail beam through a curved deflecting plate. Thus, W-beam guardrail should feed into the guardrail extruder head reliably and slow an impacting vehicle as the vehicle runs down a length of W-beam guardrail while flattening the guardrail beam and deflecting the flattened guardrail. Prior art examples of such guardrail extruder heads and further description of their operation can be found in U.S. Pat. Nos. 6,715,735 and 4,928,928.
FIG. 1a shows a top view of a prior art guardrail extruder head. FIG. 1b shows a front view of a prior art guardrail extruder head. The prior art guardrail extruder head 1 generally has a feeder chute section A, an extruder throat section B, a deflector section C and an impact head section D.
As shown in FIGS. 1a and 1b, the oncoming traffic end 2 of a W-beam guardrail 2 is pre-positioned in the feeder chute section A. Further, the guardrail end 2′ of the guardrail 2 slightly protrudes a distance E into the extruder throat section E. As a result of either a head-on or shallow angle vehicle impact on the impact head section D, the guardrail extruder head 1 moves along the guardrail 2 and the guardrail end 2′ feeds into the extruder throat section B such that the guardrail is flattened, and then the guardrail end 2′ moves into the deflector section C such that flattened guardrail is deflected out of the guardrail extruder head 1. Sometimes, the guardrail end 2′ may not protrude a distance E into the extruder throat section E due to improper mounting of the guardrail extruder head 1, unfavorable installation conditions or snow removal equipment repositioning the guardrail extruder head 1 on the guardrail 2. Such a lack of protrusion into the extruder throat may prevent the guardrail 2 from entering the extruder throat section B during an impact.
FIGS. 1a and 1b show the feeder chute section A including a top feeder channel 3a and a bottom feeder channel 3b between which the W-beam guardrail 2 is pre-positioned. A front vertical feeder chute brace 4a and a back vertical feeder chute brace 4b are coupled to the top feeder channel 3a and the bottom feeder channel 3b at one end of the feeder chute section A. A top hanging bracket 5a is attached to the top feeder channel 3a and a bottom hanging bracket 5b is attached to the bottom feeder channel 3b near the other end of the feeder chute section A. As shown in FIG. 1a, the top feeder channel 3a and the bottom feeder channel 3b in the feeder chute section A is about 36 inches long. The feeder chute section A guides the guardrail extruder head 1 along the path of the W-beam guardrail 2 during an impact.
The top feeder channel 3a and the bottom feeder channel 3b are attached to the extruder throat section B, as shown in FIGS. 1a and 1b. The extruder throat section B includes a first portion of the front plate 6a, which is a front extruder plate 6a′, and a back extruder plate 6b. The separation distance F, as shown in FIG. 1a, between the front extruder plate 6a′ and the back extruder plate 6b decreases as the front extruder plate 6a′ and the back extruder plate 6b extend from the feeder chute section A to the deflector section C. The separation distance F is maintained by the attachments of the portion of the front extruder plate 6a′ and the back extruder plate 6b to both the top plate 7a and the bottom plate 7b. A front vertical extruder brace 8 is attached to the first portion of the front extruder plate 6a′ and coupled between the top plate 7a and the bottom plate 7b. A back vertical extruder brace 9 is attached to the back extruder plate 6b and coupled between the top plate 7a and the bottom plate 7b. Further, the back vertical extruder brace 9 is at the end of the back extruder plate 6b. A post breaker 10 is attached to the back extruder plate 6b and the back vertical extruder brace 9.
As shown in FIGS. 1a and 1b, the deflector section C extends from the end of the back extruder plate 6b in the extruder throat section B to the impact plate 11 of the impact head section D. The deflector section C includes a curved second portion of the front plate 6a that is otherwise known as the deflector plate 6a″. The curve in the deflector plate 6a″ deflects the guardrail 2, which was previously flattened in the extruder throat section B second portion, as the guardrail extruder head 1 moves along the path of a guardrail 2 during an impact. The deflector plate 6a″ is attached between the top plate 7a and the bottom plate 7b. 
The impact head section D, as shown in FIGS. 1a and 1b, includes an impact plate 11 with two outwardly projecting sides. The impact plate 11 is attached to the top plate 7a and the bottom plate 7b. Further, the impact plate 11 is attached to an impact force transfer brace 12.
To assist in directing impact energy on the impact plate 11 down the guardrail 2 so as to move the head along the path of the guardrail 2 during an impact, the impact force transfer brace 12 is attached to the front extruder plate 6a in the extruder section B and coupled between the impact plate 11 and the front vertical extruder brace 8. More specifically, the impact force transfer brace 12 is coupled to the back of the impact plate 11. The coupling of the impact force transfer brace 12 to the impact plate 11 also increases the rigidity of the impact plate 11. Typically, the impact force transfer brace 12 of the prior art guardrail extruder head 1 is made of 0.25 inch thick steel plate. Further, the impact force transfer brace 12 in the prior art guardrail extruder head 1 is not located along the central longitudinal axis X-X′ of the feeder chute section A but rather the entire transfer brace 12 of the prior art guardrail extruder head 1 is offset from the central longitudinal axis X-X′.